Its probably the blower resistor. I don't know where it would be fitted on a Mk2 Escort. Some of the older Fords had these either attached to the blower motor housing or under the screen near the wipers. The nearest looking thing would be those used on Transit Vans like this: http://www.ebay.co.u...=item19d3f78643

There are none on eBay for the Mk 2 Escort, you may have to use one of those used parts sites that have access to lots of breakers.